At present, the following measurement events are defined in a LTE (long-term evolution)/LTE-A (advanced long-term evolution) system:
An A1 event, in which a serving cell has a quality higher than an absolute threshold, for turning off an on-going inter-frequency measurement and deactivating a measurement gap.
An A2 event, in which a serving cell has a quality lower than an absolute threshold, for turning on inter-frequency measurement and activating a measurement gap.
An A3 event, in which a neighbor cell has a quality higher than that of a main serving cell by an amount higher than an absolute threshold, for a coverage-based inter-frequency/intra-frequency handover.
An A4 event, in which a neighbor cell has a quality higher than an absolute threshold, mainly for a load-based handover.
An A5 event, in which a main serving cell has a quality lower than a first absolute threshold 1 and a neighbor cell has a quality higher than a second absolute threshold 2, for a coverage-based inter-frequency/intra-frequency handover.
An A6 event, in which a neighbor cell has a quality higher than that of a secondary serving cell by an amount higher than an absolute threshold, for a coverage-based inter-frequency secondary carrier adjustment.
A B1 event, in which a neighbor cell in a different system has a quality higher than an absolute threshold, for a load-based handover.
A B2 event, in which a serving cell has a quality lower than a first absolute threshold 1 and a neighbor cell in a different system has a quality higher than a second absolute threshold 2, for a coverage-based handover.
The A1/A2 event may be used for turning off or triggering inter-frequency measurement by a terminal. The A3/A5/B2 event may be used for a coverage-based inter-system/intra-system handover. The A6 event may be used for a coverage-based secondary carrier adjustment in a scenario of carrier aggregation. The A4/B1 event may be used for a load-based inter-system/intra-system handover.